DTA

#include <bits/stdc++.h>
using namespace std;
// type
typedef long long ll;
typedef long double ld;
// loop
//#define For(i, l, r, x)     for (int i = l; i < r; i+=x)
//#define ForE(i, l, r, x)    for (int i = l; i <= r; i+=x)
//#define Ford(i, r, l)       for (int i = r; i > l; i--)
//#define FordE(i, r, l)      for (int i = r; i >= l; i--)
//#define Fora(i, a)          for (auto i : a)
// I/O 
#define FAST_IO             std::ios::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
//#define PrintV(a)           Fora(ii, a) cout << ii << ' '; cout << rl;
//#define PrintVl(a)          Fora(ii, a) cout << ii << rl;
//#define PrintA(a, l, r)     for (int ii = l; ii <= r; ii++) cout << a[ii] << ' '; cout << rl;
//#define PrintAl(a, l, r)    for (int ii = l; ii <= r; ii++) cout << a[ii] << rl;
//#define Ptest(x)            return cout << x, 0;
#define setpre(n)           fixed << setprecision(n)
// pair
#define F                   first
#define S                   second
#define pii                 pair<int, int>
#define pll                 pair<ll, ll>
#define pdd                 pair<ld, ld>
// vector & !!?(string)
#define eb                  emplace_back
#define pb                  push_back
#define all(a)              a.begin(), a.end()
#define rall(a)             a.rbegin(), a.rend()
#define sz(a)               a.size()
#define len(a)              a.length()
// geometry calc    
#define pi                  acos(-1.0)
#define g_sin(a)            sin(a*pi/180)
#define g_cos(a)            cos(a*pi/180)
#define g_tan(a)            tan(a*pi/180)
// set val
#define ms0(a)              memset(a,        0, sizeof(a));
#define ms1(a)              memset(a,        1, sizeof(a));
#define msn1(a)             memset(a,       -1, sizeof(a));
#define msinf(a)            memset(a, 0x3f3f3f, sizeof(a));
// constant
const int mod1 = 998244353, mod = 1e9+7;
const int MAX_N = 100005, MAX_M = 200010;
// code
//#define int long long

int a[3][MAX_N], n, re[3][MAX_N], dp[3][MAX_N];
void Solve() {
    cin >> n;
    for (int i = 0; i < 2; i++){
        for (int j = 1; j <= n; j++){
            cin >> a[i][j];
        }
    }
    
    for (int i = 1; i <= n; i++){
        a[0][i] += a[0][i-1];
        a[1][i] += a[1][i-1];
        a[2][i] = a[1][i] + a[0][i];
    }
    
    for (int t = 0; t < 3; t ++){
        map<int, int> idx;
        for (int i = 0; i <= n; i++){
            if (idx.count(a[t][i])){
                re[t][i] = idx[a[t][i]];
            }else{
                re[t][i] = -1;
            }
            idx[a[t][i]] = i;
        }
    }
    
    for (int t = 0; t < 2; t ++){
        for (int i = 1; i <= n; i++){
            dp[t][i] = dp[t][i-1];
            if (re[t][i] != -1) 
                dp[t][i] = max(dp[t][i], 1 + dp[t][re[t][i]]);
            dp[2][i] += dp[t][i];
        }
    }
    for (int i = 1; i <= n; i++){
        dp[2][i] = max(dp[2][i-1], dp[2][i]);
        if (re[2][i] != -1) 
            dp[2][i] = max(dp[2][i], 1 + dp[2][re[2][i]]);
    }
	/*
    for (int i = 0; i < 3; i++){
        for (int j = 1; j <= n; j++)
            cout << dp[i][j] << ' ';
        cout << endl;
    }
	*/
    cout << dp[2][n];
}

signed main(){
    FAST_IO;
    int TC = 1; 
	//cin >> TC;
    while(TC--) Solve();
    return 0;
}